Harmful Volatiles Research Articles

Self-adhesive fiberboards fabricated from waste bamboo powder through biological pretreatment

Using renewable and sustainable agricultural and forestry wastes to produce bio-based materials is an effective approach for significantly reducing the environmental pollution caused by petroleum-based materials such as plastics and chemical fibers. This research aims to develop a cleaning process for large-scale production of high-performance green bio-based materials without the use of any chemical binders. The mechanical properties of self-adhesive fiberboards are improved through pretreatment with white rot fungi. By pretreating bamboo powder with biological factors like sugars and laccase produced by white rot fungi under high temperature and pressure, lignin-active molecules are formed on the surface. These active molecules can reconstruct chemical bonds between multi-fiber materials, thereby exhibiting biological adhesion. The reconfiguration of lignin molecules on the material's surface also helps prevent rapid water penetration. After biological pretreatment, the surface of bamboo powder forms a concave-convex structure, effectively increasing the area of biological adhesion during hot-pressing conditions. Compared to regular bamboo powder control samples, bio-pretreated fiberboards showed an increase in modulus of rupture (MOR) by 83.33 % and modulus of elasticity (MOE) by 100.79 %. In contrast to traditional fossil-based adhesive synthetic materials, the findings of this study circumvent the emission of harmful volatiles from chemical adhesives while effectively substituting petroleum-based synthetic materials that necessitate diverse chemical additives, which are in alignment with the principles of environmental protection and sustainable development.

Inhalation toxicity of thermal transformation products formed from e-cigarette vehicle liquid using an in vitro lung model exposed at the Air–Liquid Interface

The increasing use of electronic nicotine delivery systems (ENDS), also known as e-cigarettes, has raised serious public health concerns, particularly regarding certain vaping product additives. The solvent carrier liquid, which consists of a mixture of propylene glycol (PG) and vegetable glycerine (VG), representing the main constituents of e-liquid formulations, have in contrast received little attention in health evaluations due to their apparent harmlessness when ingested; however, they can develop into potential lung hazards when heated, aerosolised and inhaled from ENDS with a user-defined heating profile. To assess the acute toxicity of the respirable aerosol, an effect-based in vitro testing strategy was applied in dependence of the heating power settings in ENDS. Human alveolar epithelial cells (A549) were exposed to vaping aerosol at the air–liquid interface (ALI), flanked by targeted chemical analyses of reactive carbonyl species. An exploratory, semi-automated in vitro exposure system provided evidence of a positive connection between vaporisation temperature and aerosol toxicity. Thermochemical transformation of the solvent leads to the formation of both cytotoxic and genotoxic substances that may disrupt lung homeostasis. Toxicity is therefore not limited to the presence of additives, as most harmful volatiles originate from the solvent itself, ultimately related to the device power output.

A Methodology for Assessing Pollution Off-Gassing of Museum Construction Materials Using a Pyrolysis Microfurnace

Museum professionals must ensure that protective enclosures for artworks do not in fact cause damage to the objects within due to pollution off-gassing from the container’s components. Ideally, all materials used in proximity to artworks should be assessed for their potential to emit harmful volatiles. The standard approach used in the museum field, known as the Oddy test, requires significant effort and time and can produce unreliable results if not conducted by a trained staff member, all of which reduce the likelihood that proper vetting will be rigorously employed. This paper reports a methodology utilizing a microfurnace pyrolyzer coupled to a gas chromatograph with a mass spectrometer to optimize these assessments and produce actionable results with minimal time and expense. Simple confirmatory chemical tests augment the direct thermal desorption (DTD) experiment, and as a last resort, time-consuming accelerated aging tests are utilized if deemed necessary to eliminate or decide between options when a non-polluting material is not available. The successes and challenges of this developing protocol are highlighted for the planning of a recent non-traditional, multisensory exhibition, THE LUME Indianapolis, with its inaugural digital experience featuring the works of Vincent van Gogh at the Indianapolis Museum of Art at Newfields.

Reengineering Waste Boxwood Powder into Light and High-Strength Biodegradable Composites to Replace Petroleum-Based Synthetic Materials

The preparation of biocomposites from renewable and sustainable forestry residues is an effective method to significantly reduce the environmental pollution caused by synthetic materials such as plastics and synthetic fibers. This study is aimed at developing a clean process for the large-scale production of high-performance green biocomposites without involving any chemical adhesive. Adhesive-free biocomposites with superior mechanical properties were prepared using HCl ball milling pretreatment and in situ synthesis. The nano-Fe3O4 was uniformly dispersed in the cellulose matrix, and when the matrix was subjected to external forces, the stress concentration effect around the particles absorbed energy, thus effectively improving the mechanical strength of the matrix. The flexural strength and tensile strength of BWP(Fe3O4) samples were increased by 159.04 and 175.34%, compared to that of regular wood powder control samples. The lignin melts under high temperature and pressure and then forms a carbonized layer on the surface of the biocomposites during the cooling process, which prevents the rapid penetration of water from the surface and also gives the biocomposites good thermal stability. The results of this research can avoid the harmful volatiles generated by chemical adhesive than that of the traditional fiberboard process and effectively replace petroleum-based synthetic materials prepared using the addition of various chemical additives, making it conform to the concept of environmental protection and sustainability.

Online Volatile Compound Emissions Analysis Using a Microchamber/Thermal Extractor Coupled to Proton Transfer Reaction-Mass Spectrometry.

Indoor air is a complex and dynamic mixture comprising manifold volatile organic compounds (VOCs) that may cause physiological and/or psychological discomfort, depending on the nature of exposure. This technical note presents a novel approach to analyze VOC emissions by coupling a microchamber/thermal extractor (μ-CTE) system to a proton transfer reaction-mass spectrometer (PTR-MS). This configuration provides an alternative to conventional emissions testing of small objects. The dynamic emission profiles of VOCs from a representative 3D-printed model are presented as a proof-of-concept analysis. Emission profiles are related to the target compound volatility, whereby 2-propanol and acetaldehyde exhibited the highest emissions and most rapid changes compared to the less volatile vinyl crotonate, 2-hydroxymethyl methacrylate, and mesitaldehyde, which were present at lower concentrations and showed different dynamics. Comparative measurements of the emission profiles of these compounds either with or without prior static equilibration yielded stark differences in their dynamics, albeit converging to similar values after 15 min of sampling time. Further, the utility of this system to determine the time required to capture a specific proportion of volatile emissions over the sampling period was demonstrated, with a mean duration of 8.4 ± 0.3 min to sample 50% of emissions across all compounds. This novel configuration provides a means to characterize the dynamic nature of VOC emissions from small objects and is especially suited to measuring highly volatile compounds, which can present a challenge for conventional sampling and analysis approaches. Further, it represents an opportunity for rapid, targeted emissions analyses of products to screen for potentially harmful volatiles.

Harmful volatile substances in recorded and unrecorded fruit spirits

The alcohol-attributable mortality is an important issue in South-Eastern Europe, whereby consumption of homemade spirits is stated to be one of the leading causes. Presence of harmful volatiles in spirits in Serbia was investigated in 26 recorded and 127 unrecorded fruit spirits, collected in 2020 and analysed using GC-FID methods. Statistical analysis confirmed higher content of ethanol, ethyl acetate, n-propanol and iso-butanol in unrecorded spirits. Regarding concentration limits proposed by the Alcohol Measures for Public Health Research Alliance, the one for methanol was exceeded in 4% of recorded and 17% of unrecorded spirits, for acetaldehyde in 4% of unrecorded and for higher alcohols only in one recorded spirit. Risk assessment, conducted using a margin of exposure approach, showed that spirit consumption, even at average level, posed a risk due to their high ethanol content. Regarding acetaldehyde, for males the risk was indicated starting from the regular drinkers only scenario (mean MOE 9937 for recorded and 9123 for unrecorded spirits) and for females who were chronic heavy drinkers of recorded (2324) or unrecorded spirits (1644). Chronic heavy drinkers of both sexes were in the risk of methanol and higher alcohols in case of exclusive consumption of unrecorded spirits.

Real-time monitoring of the emission of volatile organic compounds from polylactide 3D printing filaments

Establishing the emission profile of volatile organic compounds generated during fused deposition modeling 3D printing using polymer filaments is important in terms of both understanding the processes taking place during thermal degradation of thermoplastics, and assessing the user's exposure to potentially harmful volatiles. However, obtaining detailed, real-time qualitative and quantitative results poses a challenge. In this paper solid-phase microextraction-gas chromatography-time-of-flight mass spectrometry and proton transfer reaction time-of-flight mass spectrometry were used to identify and monitor the emission of volatiles during thermal degradation of polylactide filaments and during 3D printing. Filaments of two different grades and three colours were used. It was possible to obtain detailed, time- and temperature-resolved emission profiles of the main products of thermal decomposition of lactide and polylactide 3D printing filaments at concentration levels of a few μg/g. This revealed different temperature-dependent emission characteristics of particular volatiles, such as, among others, lactide, acetaldehyde, acetic acid, and 2-butanone between various polylactide 3D printing filaments. This approach can be used to monitor the emission associated with printing with various other types of polymer 3D printing materials.

Monitoring the BTEX Volatiles during 3D Printing with Acrylonitrile Butadiene Styrene (ABS) Using Electronic Nose and Proton Transfer Reaction Mass Spectrometry.

We describe a concept study in which the changes of concentration of benzene, toluene, ethylbenzene, and xylene (BTEX) compounds and styrene within a 3D printer enclosure during printing with different acrylonitrile butadiene styrene (ABS) filaments were monitored in real-time using a proton transfer reaction mass spectrometer and an electronic nose. The quantitative data on the concentration of the BTEX compounds, in particular the concentration of carcinogenic benzene, were then used as reference values for assessing the applicability of an array of low-cost electrochemical sensors in monitoring the exposure of the users of consumer-grade fused deposition modelling 3D printers to potentially harmful volatiles. Using multivariate statistical analysis and machine learning, it was possible to determine whether a set threshold limit value for the concentration of BTEX was exceeded with a 0.96 classification accuracy and within a timeframe of 5 min based on the responses of the chemical sensors.

Improvements of Developed Graphite Based Composite Anti-Aging Agent on Thermal Aging Properties of Asphalt

To reduce the thermal-oxidative aging of asphalt and the release amount of harmful volatiles during the construction of asphalt pavement, a new composite anti-aging agent was developed. Since the volatiles were mainly released from saturates and aromatics during the thermal-oxidative aging of asphalt, expanded graphite (EG) was selected as a stabilizing agent to load magnesium hydroxide (MH) and calcium carbonate (CaCO3) nanoparticles for preparing the anti-aging agents of saturates and aromatics, respectively. Thermal stability and volatile constituents released from saturates and aromatics before and after the thermal-oxidative aging were characterized using the isothermal Thermogravimetry/Differential Scanning Calorimetry-Fourier Transform Infrared Spectrometer test (TG/DSC-FTIR test). Test results indicate that anti-aging agents of EG/MH and EG/CaCO3 effectively inhibit the volatilization of light components in asphalt and improve the thermal stability of saturates and aromatics. Then, the proportions of EG, MH, and CaCO3 added in the developed composite anti-aging agent of EG/MH/CaCO3 are 2:1:3 by weight. EG/MH/CaCO3 plays a synergetic effect on inhibiting the thermal-oxidative aging of asphalt, and reduces the release amount of harmful volatiles during the thermal-oxidative aging after EG/MH/CaCO3 is added into asphalt at the proposed content of 10 wt.%. EG plays a synergistic role with MH and CaCO3 nanoparticles to prevent the chain reactions, inhibiting the thermal-oxidative aging of asphalt.

Developed compound flame retardant for bitumen based on thermal properties of four components

Bitumen produces a lot of harmful gaseous products and heat at high temperature, endangering human health and ecological environments. To develop an efficient compound flame retardant (FR) for suppressing thermal decomposition and volatile release of bitumen, the suppressing effects of matched halogen-free FR for each bituminous component was first discussed, and then a compositional formulation was proposed to develop a new compound FR for bitumen, suppressing bituminous thermal decomposition and volatile release. Results indicated that the matched FR inhibited endothermic and exothermic reactions, lowered the thermal decomposition rate, and retarded the whole thermal decomposition progress of each component. Also, the dynamic release process of emitted volatiles from each component was suppressed by the selected FR. The release amount of main volatiles was decreased, but CO2 and H2O were still main gaseous products from each bituminous component. Additionally, the superimposed and voidless barrier layer was generated owing to the synergic effects of matched FRs. It suppressed the volatilization and thermal decomposition of flammable volatiles, and hindered the heat transfer and oxygen supply, improving the thermal stability of each component. Added hydroxide FRs showed comprehensive effects of cooling, dilution, adsorption and neutralization, and the generated active oxide facilitated the intumescent layer of expandable graphite to be carbonized. The selected FR played flame retarding and smoke suppressing roles on thermal decomposition of each component. Finally, the compositional formulation of compound FR was proposed to develop a new compound FR for bituminous materials based on the suppression of matched FR on each bituminous component. The developed compound FR efficiently suppressed bituminous thermal decomposition, and lowered the release amount of harmful volatiles and heat when exposed to high temperature.

Evaluation of pyrolysis and combustion products from foundry binders: potential hazards in metal casting

The aim of this paper is the comparison of the thermal destruction course of one of the commercially available binders applied in the ALPHASET technology in dependence of the temperature, heating rate and the character of the atmosphere (inert, oxidising or reducing). The thermogravimetric analysis/differential scanning calorimetry/Fourier-transform infrared spectroscopy (TG/DSC/FTIR) system allowed for real-time analysis of the composition and intensity of gases emitted during slow heating in the inert and oxidising atmospheres. In addition, the TG/DTG/DSC investigation of the binder was performed in the reducing atmosphere. The pyrolysis gas chromatography coupled with mass spectrometry system allowed for the analysis of gases evolved at very fast heating in the inert atmosphere (pyrolysis) as a function of temperature. It has been proven that the type and amount of the gases emitted is highly dependent on the temperature, heating rate and the atmosphere in which it is performed. The highest versatility of harmful volatiles is produced during heating in the inert atmosphere. This type of atmosphere is present in the closest proximity of the liquid metal. Thus, to reduce the risk of exposure of the foundry workers, the extraction of the casting should be done under the hood, and sufficient personal protective equipment should be used.

Vaporized vs Combusted Nicotine: A Biomechanical Comparison of Achilles Tendon Healing in a Rat Model

Category:Basic Sciences/BiologicsIntroduction/Purpose:The negative effects of smoking have been well documented following orthopedic injury. Though nicotine has been shown to be detrimental to musculoskeletal tissue healing, nicotine in the form of “Vaping” is being increasingly used as a perceived healthier alternative to actual smoking and may theoretically obviate many of the harmful volatiles and chemicals contained within combusted tobacco that are additionally harmful to musculoskeletal healing. Our objective was to evaluate the biomechanical and histological effects on Achilles tendon repair between rats that inhaled combusted tobacco, versus those with isolated nicotine exposure via vaping, versus a control group.Methods:54 Sprague Dawley rats were randomly placed in a control, vaping, or cigarette cohort. Each group contained 17 rats and exposure occurred six days per week. The smoking cohort was exposed to 2 unfiltered University of Kentucky research cigarettes in a previously validated smoking chamber (Figure 1). The vaping group was exposed to e-cigarette vapor with equivalent nicotine exposure over ten minutes at a flow rate of 2.4 L/min. The control group was placed in the smoking chamber with room air flowing through the chamber. All rats received their respective daily exposures for 4 weeks prior to surgery when surgical transection and repair of the Achilles tendon was performed. Following surgery, the rats continued 2 additional weeks of smoking, vaping, or control exposure. After sacrifice, Achilles tendons were harvested and tested with controlled tension to failure. Histology (n = 2 per group) was performed with a standard H&E protocol.Results:Tensile load testing evaluated maximum force to rupture and tissue stiffness amongst the three cohorts. The control group demonstrated highest mean tensile strength of 41.0 N (18.3-55.1 N), with the cigarette cohort having the second highest mean tensile strength at 37.3 N (14.0-54.7 N), and finally the vaping group had the lowest at 32.28 8 N (17.8-45.1 N). One-way ANOVA with heterogeneity of variance was used for evaluation. There was a significant difference detected in load to failure when comparing controls to e-cigarettes (p=0.026). No statistical difference was seen between controls vs cigarettes (p=0.35). Histological analysis demonstrated no difference among groups.Conclusion:Our investigation demonstrates that, in a rat model, isolated nicotine exposure via ”vaping” significantly impedes biomechanical healing properties of Achilles tendon surgical repair. Though smoking resulted in a lower maximum force to failure as compared to control in these samples, this difference was not significant. While E-cigarettes are often utilized as a perceived “safer” alternative to smoking combusted tobacco, this study suggests that use of e-cigarettes may be more detrimental to tendon healing than combusted tobacco in a rat Achilles model.

Processing high-performance woody materials by means of vacuum-assisted resin infusion technology

High-performance materials derived from natural wood have been vigorously developed, however, their commercialized products are very limited owing to the lack of industrial production efficiency and increase of environmental concern. This study is aimed at developing a clean process for large-scale production of high-performance woody materials without involving any chemical methods. The industrialized vacuum-assisted resin infusion (VARI) process was initially applied to solid wood for manufacturing woody materials with excellent flexural performances. VARI process can provide better control over harmful volatiles generated by resins than that of the traditional open mold techniques, making them compliant with “clean production”. The porosity was reduced from 66.0% to 33.8% after infusing epoxy into wood through the VARI process, and further reduced to 22.6% after being compressed. The flexural modulus and strength were significantly increased by 142.2% and 142.8%, respectively. The flexural strength (304.9 MPa) reached the range of alloy, between Alloy 2024-T3 (345 MPa) and Steel alloy 1040 (260 MPa). Due to its relatively low density, the specific flexural strength was only slightly lower than diamond. The dramatic reduction of porosity was deemed to be the major contribution to those improvements. The fabrication of high-performance woody materials does not use chemical treatment; therefore, it could be considered as a clean production. Additionally, the contribution to clean production of this study was further confirmed by life-cycle assessment (LCA). The comparisons of environmental impacts of the woody material, steel alloy and aluminum alloy were carried out using LCA, revealing that the global warming, acidification, human health (HH) cancer, HH noncancer, HH criteria air pollutants, eutrophication, ecotoxicity, smog, natural resource depletion, habitat alteration, and ozone depletion, were reduced by 1.72–667.06 times when the woody material was used to replace steel alloy, while were reduced by 7.34–636.21 times when the woody material was utilized to replace aluminum alloy, respectively.

Comparison of Achilles Tendon Healing After Exposure to Combusted Tobacco, Vaping, and Control in a Rat Model

Objectives: The negative effects of smoking have been well documented following orthopedic injury. Though nicotine has been shown to be detrimental to musculoskeletal tissue healing, nicotine in the form of “Vaping” is being increasingly used as a perceived healthier alternative to actual smoking. It may theoretically obviate many of the harmful volatiles and chemicals contained within combusted tobacco that are additionally harmful to musculoskeletal healing, beyond just nicotine. The literature has yet to establish the benefits, or lack thereof, to exposure of e-cigarettes and their effect on tendon healing when compared to traditional combusted tobacco. Our objective was to evaluate the biomechanical and histological effects on Achilles tendon repair between inhaled combusted tobacco versus isolated nicotine exposure via vaping versus a control group in a small animal (Sprague Dawley Rat) model. Methods: 54 Sprague Dawley rats were randomly placed in a control, vaping, or cigarette cohort. Each group contained 17 rats for exposure and they were exposed six days per week. The smoking cohort was exposed to 2 unfiltered University of Kentucky research cigarettes in a smoking chamber (Image 1). The vaping group was exposed to e-cigarette vapor with equivalent nicotine exposure as compared to the cigarette group, over ten minutes at a flow rate of 2.4 L/min. The control group was placed in the smoking chamber with room air flowing through the chamber. All rats received their respective daily exposures for 4 weeks prior to surgery where transection and repair of the Achilles tendon was performed. Following surgery, the rats received 2 additional weeks of smoking vs vaping vs control exposure. After sacrifice, Achilles tendons were harvested and tested with tensile and a load to failure model (Image 2). Histological samples were sent for analysis. Results: Tensile load testing evaluated maximum force to rupture and tissue stiffness amongst the three cohorts. The control group demonstrated highest mean tensile strength of 41.0 N (18.3-55.1 N), with the cigarette cohort having the second highest mean tensile strength at 37.3 N (14.0-54.7 N), and finally the vaping group had the lowest at 32.28 N (17.8-45.1 N). One-way ANOVA with heterogeneous of variance was used for evaluation. There was a significant difference noted in load to failure when comparing controls to e-cigarettes (p=0.026). No statistical difference was seen between controls vs cigarettes (p=0.35). Histological analysis is in progress. Conclusion: Our investigation demonstrates that in a rat model, isolated nicotine exposure via ”vaping” significantly impedes biomechanical healing properties of Achilles tendon surgical repair. Though smoking resulted in a lower maximum force to failure as compared to control, this difference was not significant. While E-cigarettes are often utilized as a perceived “safer” alternative to smoking combusted tobacco, this study suggests that use of e-cigarettes may be more detrimental to tendon healing than combusted tobacco in a rat Achilles model.

Thermal behaviors and harmful volatile constituents released from asphalt components at high temperature.

Asphalt binder releases lots of heat and harmful volatiles at high temperature. To further understand thermal behaviors, dynamic release and toxic constituents of emitted volatiles during the combustion of asphalt binder, such fractions as saturates, aromatics, resins and asphaltenes (SARA) were first prepared. Thermal behaviors, volatile constituents and combustion residue microstructures of SARA fractions are discussed. Results indicate that polymerization degree of asphalt binder is high and the content of polycyclic aromatic compounds is large. Combustion processes of resins and asphaltenes only show single-stage exothermic reactions, but other two fractions present obvious multi-stage combustion reactions. As the heating rate is raised, the incomplete combustion of SARA fractions is increased, and more volatiles are released. Main volatiles released from SARA fractions are inflammable, toxic, corrosive or explosive compounds, and such common volatiles as acetaldehyde and propane are released from each SARA fraction. More toxic volatiles are released at combustion stage I, but macromolecular volatiles are mainly released at stage II. Volatile release behaviors of saturates and aromatics are more obviously affected by the heating rate. Combustion residues show more intact morphologies from saturates to asphaltenes, and mainly contain C, O and S elements. Asphalt binder is hazardous material at high temperature.

Activation of glucose with Fenton’s reagent: chemical structures of activated products and their reaction efficacy toward cellulosic material

Abstract The release of harmful volatiles, such as formaldehyde, is a major issue of the chemical modification of wood that limits the utilization of the modified wood in indoor environment. In this study, glucose (Glc) was activated with Fenton’s reagent under various conditions and the chemical structure of the activated Glc was characterized. Also, the reactivity of the activated Glc toward filter paper as a wood model was evaluated. The results show that the H2O2 concentration controlled the activation ratio of Glc. Additionally, the Fe(II) concentration and activation temperature determined mainly the oxidation reaction rate. The Fenton reaction in an acidic solution resulted in higher activation efficacy of Glc and better fixation in the filter paper, compared to the reaction in an alkaline solution. The Glc cannot be fixed in the filter paper, but the activated Glc exhibited a fixation ratio of up to 48.2% due to the formation of carboxyl and aldehyde groups, as evidenced by Fourier-transform infrared (FTIR) spectroscopy and gas chromatography-mass spectrometry (GC-MS). It was demonstrated that activation of Glc with the Fenton’s reagent is a feasible and eco-friendly approach and the activated products have a high potential for wood modification.

Investigation of the Effect on Tribological Properties of the use of Pinus Brutia Cone as a Binder in Brake Pads

Phenolic resin is invariably used as binder material for friction composites. But alternative materials are considered alternatively to phenolic resin due to negativities such as poor shelf life, harmful volatiles during processing, the need for addition of curing agent before shipment, shrinkage and voids in final products. For these reasons, pinus brutia cones are ground and pulverized and added to the brake lining content at different rates and thus 3 different samples were produced. The wear and friction tests of these samples were made on pin-on disc type brake lining test machine. After this, the density of the samples was determined by using Archimedes scale. The hardness was determined in the Brinell tester. And finally, the microstructure properties of the samples were determined by using a scanning electron microscope (SEM).

Evaluation of the non-aldehyde volatile compounds formed during deep-fat frying process

To investigate the non-aldehyde volatile profile resulting from deep-fat frying, volatile compounds formed during the processes of heating soybean oil (SO), frying wheat dough (WD), and frying chicken breast meat (CBM) were comparatively studied. By using gas chromatography-mass spectrometry and internal standard method, alkanes, alkenes, alkynes, alcohols, ketones, nitrogen-containing volatiles (NCVs), and other volatiles were qualitatively and relatively quantitatively detected. NCVs were detected only in CBM-fried oil samples. Some volatiles (e.g. 2-pentylfuran and 2-pentylpyridine) were observed to increase in concentration, whereas others (e.g. 4-methyl-1,4-heptadiene and 7-methyl-3,4-octadiene) were observed to first increase and then decrease in concentration as the heating or frying time increased. Reduced quantity and concentrations of volatiles were observed in the food-fried oil samples which might be related to the intensified reactions induced by food components. The detection of some harmful volatiles in considerable concentrations indicated further attention might be paid to the safety of deep-fat frying.

Influence of different types of binder in non-asbestos-organic brake lining materials: A case study on inertia brake dynamometer

Phenolics and alkyal benzene modified versions are commonly used as binder in friction materials. However, the poor shelf life, evolution of harmful volatiles during processing, and shrinkage/voids in final products are some of the major problems associated with these binders. In order to overcome these, a binder based on ploybenzoxazine (which was synthesized in laboratory and presented in our previous work) was used as alternative resin in this work. Hence present case study discusses the comparative behavior of these three different binders (ploybenzoxazine, phenolic, and alkyal benzene modified). Brake lining materials based on these binders were developed as per standard industrial practice in laboratory and tribo-evaluated on inertia brake dynamometer. It was observed that the brake linings developed with the ploybenzoxazine binder performed better in all aspects (friction, wear, fade) compared to traditional binders such as phenolic and alkyal benzene modified versions.

A TG-FTIR investigation into smoke suppression mechanism of magnesium hydroxide in asphalt combustion process

In this study, the combined thermogravimetry-Fourier transform infrared spectroscopy (TG-FTIR) technique was employed to analyze the influence of magnesium hydroxide (MH) on the volatile release in asphalt combustion process. The experimental results indicate that the combustion processes of asphalt and asphalt/MH composite are both multistage, and the volatiles are different in each temperature interval. After adding MH into asphalt, the temperature rise of asphalt matrix is inhibited due to MH thermal decomposition. Firstly, the water vapor dilutes or absorbs some carbon particles to hinder the soot nucleation and aggregation, and then smoke density is decreased. Secondly, the active magnesium oxide (MgO) promotes the tight charring layer generation on the asphalt surface. The layer hinders carbon particles and flammable volatiles from releasing out of asphalt, and the starting release time of volatiles is also deferred. The incomplete combustion residue of asphalt is absorbed by MgO to prevent droplet generation at high temperature. Also, the smoke nuclear and soot particles are reduced by the sorption of MgO. Finally, because MgO is alkaline, the acid combustion products are neutralized quickly to generate some compounds in asphalt. Because of the above effects of cooling, dilution, absorption and neutralization from MH, the purpose of smoke suppression is achieved, and the release amount of harmful volatiles is reduced, without any generation of harmful substances during asphalt combustion process. It is concluded that MH may be used as a new kind of environment-friendly and efficient smoke suppressant for asphalt.